, Former Research Professor, Bioproducts and Biosystems Engineering
Bruce Wilson, Professor, Bioproducts and Biosystems Engineering
Road deicing is a major cause of chloride impairment in Minnesota's urban waters. The goal of this study was to develop an adaptive management (AM) strategy to reduce chloride impacts caused by deicing operations. The AM process was informed by the research team?s analysis of chloride movement in a residential watershed, providing feedback to the street department of the team?s collaborator, the City of Edina. A key finding was that most the chloride movement occurred during a small number of events, with half of annual chloride movement occurring in less than 50 hours during each of the two years of study. This observation means that targeting these events might be a more effective way to reduce chloride impacts than more generalized approaches. Researchers also found that a significant amount of chloride added to streets during deicing accumulated in roadside snow piles, likely contributing to groundwater contamination. To address this concern, researchers developed a spreadsheet tool to estimate steady-state (long-term) chloride concentrations in groundwater. Scenario analyses indicated that groundwater chloride levels in highly urbanized watersheds would eventually exceed water quality standards. Researchers developed a second model, intended for use by urban planners, to estimate the impact of changing the percentage of salted impervious surface on chloride movement in redeveloped watersheds.